Wireless signaling system



March 19, 1929. H. w. NlcHoLs V V WIRELESS -SIGNALING SYSTEM Filed NOV;l 26. v1920 n /f Mumllkllllllllll Patented Mar.. 19, 1929.

UNiTED STATES PATENT eerie-1:.

HAROLD w. nier-ions', or MArLE'Woo'D, naw JERSEY, Assrsuortro WESTERN ELEC- TRIO COMPANY, NcORroRA'rED, or NEW YORK, n. Y., A CORPORATION or NEW YORK.

WIRELESS SIGNALIG SYSTEM.

application filed November 26, 1920. seran No. 426,429.

This invention relates to a signaling system and more particularly to an arrangement whereby interaction between a plurality ot transmitting circuits of a multiplex station resulting in cross talk` may be eliminated. Y

' In any system of multiplex wireless transmission in which two or more modulated carrier Waves are impressed upon an antenna system, which comprises either antennae spaced apart or separate portions of a unitary structure, there is a coup-ling connection between the several antennaev due to the capacity between each antenna and ground, the capacity between the antennae, mutual induction between the antenna circuitsv and the common resistance path of the several antennae. f

In such systems each channel is provided with an amplifier for the modulated carrier current supplied to the antenna with which it is associated, and, owing to the coupling` connection described above, voltages are induced in the output circuits ot each of the-amplifiers included in the other channels when energy is radiated from the antennae, and as a consequence there is crosstalk;- f

This coupling resulting in cross-talk, can be eliminated by making the antennae noninductive,but this is not veryv practical ovving to the sacrifice of power-entailed.

011e object `oi this invention is toprevent cross-talk in multiplex transmitting system. f

Another object is to provide an arrangement whereby the effect et the coupling connection due' to the mutual impedance between a plurality oi adjacent circuits, may be neutralized with a' minimum loss of power.

According to this invention these' objects may be accomplished by supplying each am- Jlifier With voltages of proper phase and value to neutralize the undesirable potentials induced in its output circuit rby theradiation of modulated current ot other car; rior Jreojuencies than that supplied to the antenna through the particular amplifier under consideration.

@ne method ci' accomplishing these objects and others which will appear vas the description proceeds is shown, by way of example, in the attached dra-wings, in iva .b1

Figure l shows the invention applied to a system employing two antennae and Figure 2 illustrates the application of the invention to a transmission system utilizing three antennae9 some features ot this arrangement being omitted for the sake of simplifying the drawing and others being schematically@ shown.l 1

In this disclosure an amplifier, herein shown for illustrative purposes only as of the audion type, is associated with an antenna to supply modulated carrier current of a definite frequency thereto for signal transmission purposes and by means of compensating circuits5 with the antennae upon which the other signal frequencies are impressed.

The compensating circuits may be either directly or inductively coupled to the antennae with which they are associated, but provision shouldv be made to regulate the voltage supplied to the amplifiers through these circuit-s so that it is of just sufficient magnitude to neutralize the induced voltages in their plate circuits. An adjustable coupling between the respective antennae. and the associated compensating circuits may be used for this purpose7 though it is obvious that any other method of regulating the voltage fed back may be employed.

As is .well known 'the compensating voltages derived from the different antennae will not be in phase with the undesirable voltages induced in the plate circuits of the amplifi-4 ers, as a result of radiation oi signaling current from the otherantennee, and hence, to correct this out-o'-phase condition Votl the voltages iedback,` the compensating circuits should include phase adjusting devices each adaptedto regulate' the phase of the voltage derived from the@ antenna with which the particular compensating circuit is associated. i

For a complete disclosure of the invention reference will nou be made to the attachedldrawings. y

Referring to Fig. l, separate antennae l and 2 are shown, the earths surface being represented by theline 3--? to whichfeach antenna is separately grounded. Separate current sources 4 and 5' are adapted to supply modulated current of di'ferent carrier l'requencics to the antennm l, and 2 respectively.

The :modulated current supply Vserene' 4l,

soV

which comprises a source of carrier current, the frequency of which may be represented by f', and means for modulating it, is connected to the input circuit of the amplifier 7 through the transformer 6. The amplifier is herein shown, for illustrative purposes, only, as a vacuum tube 7 enclosing a heated filament or cathode 8, an impedance control element or grid 9 and a plate 10. Amplified current is supplied to tbe antenna 1 by the transformer 11, the primary of which is included in the output circuit of the amplifier and the secondary of which is included in the antenna circuit.

The antenna 2 .is supplied with amplified modulated carrier current of a frequency through amplifier 1e'.- and the transformer `12, the primary winding of the latter being included in the plate circuit of the tube while its secondary winding is connected in the antenna circuit. Modulated current from source 5 is supplied to the input circuit of the said amplif ing tube through the transformer 13. l/Vhiie separate sources of current supply are herein shown ya single source adapted to supply currentsof different frequencies may be used. Moreover, as the n ethod of connecting the amplifier and antenna is not an essential feature of the invention, any other method of interconnecting them may be employed.

The capacitive coupling between the two antennae 1 and 2 is indicated bythe circuits 15, shown in dotted lines connecting them, which includes the condcnsers C; and the capacity between`V each antenna and ground is represented by condensers C and C which are indicated as connected between said v antennae and ground by the dotted circuits 1G and 17, respectively.

Due to these capacitive couplings, mutual rinduction Iand the ground connection between these antennae a voltage will be induced in the plate circuit of the amplifier' 7 when 1 signaling current 'is transmit-ted from antenna 2 and in like manner radiation of energy from antenna 1 will induce a voltage in the plate circuit of the amplifier 14. `When the antennae are in operation simultaneously an induced voltage will be present in the plate circuits of bothv amplifiers and consequently there will be crosstalk, with the attendant confusion of signals and impairment of their quality.

linductively associated with the secondary winding of the transformer l1 is a winding 18 shunted by a condenser 19, this latter combination constituting a pliasefadjusting device, .which is connected by the conductors 20 to the grid circuit of the amplifier 14. In a similar manner the secondary of the transformer 12 has a phase adjusting circuit 21-22 associated with it which is connected to the grid circuit of the amplifier 7 by the conductors 23.

In case it is found necessary ordcsirable the amplitude of the oscillations fed back to the `grid circuits of the ampliers may be increased before being impressed thereupon by means of auxiliary amplifiers 24, adapted to be included in each of the connecting cir?. cuits 20 and 23 by means of the switches 28.

Referring to Fig. 2 in which the invention is shown applied to a transmitting station which involves the use of three antennae, the

tennae AN, ANl, and AN2 and between the separate antennae and ground are indicated by the dotted lines extending between these antennae and from the separate antenna), to ground, which include condensers C, Eto CT'. The capacitive coupling between the antennae AN and AN2 is represented by condensers (3 between the antennae AN and ANl by the ccndensers C, and between the antennae AN l and AN2 by the condensers C3'. The coupling between the antenna AN and ground is represented by the condenser C, and part of C5; that between AN and ground by parts of condensers C, and CG and between antenna AN2 and ground by Vpart of condenser GG and condenser C7. Y

As herein shown, a compensating voltage is derived. from the antenna AN which, after being adjusted by the phase regulatingdevice PA, flows through the compensating circuit 10 and the branch circuits 30 and 31 to the grid circuits of the amplifiers AM,L and AM2, respectively. l

In like manner voltage derived from antenna AN1 has its phase adjusted. by the phase regulating device PAM flows through the compensating circuit 41 and. through the branch circuits 38 and 34 which are respectively connected'to the grid circuits of the amplifiers AM and AM2 and potential derived fromthe antenna ANL', after having its phase adjusted by the phase regulating device PAZ, traverses the circuit l2 and the branch circuits 35 and to the grid circuits of the amplifiers AM and AMl respectively.

As described, it will be seen that this system includes-a conductive path between each of the phase adjusting devices and the amplifier asosciated with the Y. samey antenna through the associated compensating and branch circuits. In order to prevent the transfer of voltage over this path a unidirectional conductive device 37, herein shown by way of example as of the vacuum tube type, is included in each branch circuit.

Further description ot these devices, otherwampliiei's for than to state that theymustbev operated so that no-moduliation ofthe voltage traversing unnecessary sincelthe operation of such de vices is now well understood.. f f i;

To avoid positive polarization ofthe grid elements of the `main amplifiers,l ther output` rl circuit of the unidirectional:devices should be souconnected to .the input circuits oi the main'amplifiers that n'ofdi-rect current can iow thereto from the plate sourcesffor these devices. One simple method of accomplish-l ing this would be to couple the plate circuits ot the unidirectional devices to the input circuitoiE the main ainpliliers inductively, as shown at 38. r Y

Line' 3-3, as in Fig. l, indicates the surface of the earth to which the antennae are separatelygrounded. 'v

From` the-preceeding description it will be obviousthat by a mere duplication ot the compensating circuitsyeachprovided With a properly-fadjustedwphase shitting. device connected' between the antennae andthe amplifiers in the manner describedabove, the principles' otthis' invention ican be applied to a multiplex transmitting -fsystem vadapted o use with any number of signaling channes. 'f' i @ne voi `the essentialwfeatures lGif-this in pensating circuits, thelosses in these circuits negligible. Furthermore, this result'yisrv accomplished by means of the elements nor nially used 4for signaling purposes.

ln case a small auxiliary ampliiier is usedin the compensatingcircuits as-hcreinbefore suggested the additional power required-is relatively small, since it isinerely that supplied by the plate-'circuit battery of said auxiliary amplifiers.

While a particular arrangement involvingv certain elements-and connections has been specilically .describedin this speciication, in order to disclose completely and clearly the nature or the invention, it is to be understood that this invention is not limited thereby but solely by the scope of the appended claims.

What is claimed is:` Y l. An electric system comprising a plurality o'l adjacent transmission circuits, means including anamplifier for supplyingy an alternating current to eachr otsaid trans'- mission circuits, and means including sait tion therebetween.

2. ififmultiplex wireless transmitting sys-` tem compri" 't pair of antennae, a signal transferring energy between said circuitsfor coiniiensating tor interacchannel associated with, each antenna including` an amplifier and means associatedI with each antenna for supplying a voltage to the inputv circuit oiithe amplitierasso.

Aciated with the other antenna 'for coni- ,pensating 'for interaction between said antennae.

3. i multiplex..wireless transmitting sys tem comprising a plurality of antennae, a signal .channel associatedivvith each antenna including 'an ainpli'ier and means associated with each antennapior supplying voltages to the input circuits of the amplifiers associated.

with the other antennae for compensatingnl tor interaction between said antennae.

4:. A wireless transmission system comprising a plurality of antennae, an amplifier associated with each antenna for supplying signal current thereto, and means including said ampli'iers for compensating 'for inter- .,action between said antennae.

5. A Wireless signaling system including a plurality of antenn, a signal circuit associated with one of said antennae including ampliiier for transmitting energy thereto,

and means associated with the other of said antennae for supplying a voltage to the. inu put circuit otsaid amplifier for compensating 'for interaction between said antennae.`

6. ilv Wireless signaling system .including ay plurality oi" antennae, signal circuits associated with said antennae, and means. ma cludinc` .an ampliher toi' transmitting energy e .A iromone antenna to the signal. circuit-s or the other.antennae tor compensating for interaction between said antennae. Y

. 7. rmulti alex Wireless transmi tine' s stem comprising a pair of antennae andk a signal channel associated with cach antenna including anamplifier., means associated with each antenna supply source 'for deriving a voltage there'linm and means including a phase adjusting device tor connecting said .deriving means to'` the input circuit of the amplifier associated with the other antenna.

8. A multiplex wireless signal transmitting system comprising a plurality of antennae and a signalchannel associated with each antenna. including an amplifier, means associated with each antenna supply source for deriving a voltage therefrom and means .including a phase adjusting device and a unidirectional conducting ldevice for connecting said deriving means to thel input circuits of the amplifiers associa-ted with the other antennae. Y y

9. A multiplex wireless tiansmitting` system comprising a pair of' antennae, a plurality of arnpli;` rs and a plurality ,of

sources of modulated carriercurrent oi'Y di'f- `device for applying saidkvoltage to neutralize an undesirable voltage induced in 'the plate circuit of the amplifier associated with the other signal channel.

11,. A wireless signal system comprising a pair of antennae, a signal channel including an amplifier associated with each antenna, and a circuit interconnecting each antenna and the amplifier included in the other signal channel for transfer g energy to compensate for interaction between sa i antennae, said circuits cach including a phase regulating device and an amplifier.

12. A wireless signal system con'lprising a plurality of antennae, a si nal channel including an amplifier associated with each antenna and circuits connecting each antenna with the amplifiers included in the other signal channels for transferring energy to compensate for interaction between said antennae, each circuit including a phase regulating device and an amplifier.

13. An electric system comprising a plurality of adjacent transmission circuits, an alternating current supply source for each transmission circuit and a circuit connecting each source with the other transmission circuit for transferring energy to compensate for interaction'between said transmission circuits, said transferring circuits including amplifying means.

1er.. An electric system comprising a plurality of adjacent transmission-circuits, an alternating current supply source for each circuit and circuits connecting each source with the other transmission circuits for transferring' energy to compensate for interaction between said transmission circuits, each transferring circuit including amplifying means.

15. A wireless transmitting' system comprising a plurality' of transmitting antennae and means including` an. amplifier associated therewith for: compensating for interaction between said antennae.

16. A wireless system comprising a plurality of transmitting antennae, a signal channel for each antenna and means associated with each antenna and the signal channels of the other antennae for compensating the interchange between said antenna and the signal channels associated with the other antennae for interaction between said antennae. e.

17. The combination in a radio signaling system of two transmitting antennae in proximity to each other, a source of high frequency energy of one frequency connected to one antenna, a source of high frequency energy of a different frequency connected to the other antenna, and means for preventing an undesired reaction between the two antennae by reason 4of the mutual capacity between them.

18. The combination in aradio signaling system of two transmitting antennae in proximity to each other, a source of high frequency energy of one frequency connected to one antenna, a source of high frequency energy of a different frequency connected 'to the other antenna, and an inductive connection between the two antennae for neutralizing the mutual capacity between them at one desired frequency.l

19. The method of operating a radiating system comprising two adjacent transmitting antennae, one having a source of high frequency energy of one frequency connected thereto and the other having a source of high frequency of a different frequency 'connected thereto, which consists in neutralizingV the mutual capacity between the two antennae for the frequency of one of the sources, and preventing undesired effects upon the antenna connected to the source of that fre- Y quency from currents set up in the other antenna.

20. The combination in a radio signaling system of two transmitting antennae in proximity to each other, a source of high frequency energy of one frequency connected to one antenna, a source Vof high frequency energy of a different frequency connected to the other antenna, and means connecting the two antennae for neutralizing the mutual capacity between them at one desired frequency. Y

21. A circuit arrangement comprising two senders having their antennae electrostatically coupled, and arranged to operate simultaneously, and means for neutralizing the effect of the coupling between the antennae with respect to a part only of one of the senders, said means comprising a circuit connected in parallel with said part and coupled with the other sender so as to receive compensating potential therefrom.

22. A circuit arrangement comprising two senders having their antennae electrostatically coupled, and arranged to operate simultaneously, and means for neutralizing the effect. of the coupling between the antennae with respect to a part only of one of the senders, said means comprising a circuit connected in parallel with said part and including a coil coupled with a coil on the other sender so as to transmit compensating lOO potential from the last mentioned sender to said part.

23. In combination, a plurality of circuits having portions thereof coupled together, means for neutralizing the effect of the coupling between said portions on a part only of any one of said circuits. 24. In combination, a plurality of circuits having portions thereof electrostatically coupled together, inductive means for neutralizing the effect of the coupling between said portions on a part only of any one of said circuits.

25. In combination, a plurality of circuits having portions thereof coupled together, one of said circuits having a part which it is desired to keep free from thedisturbing influence of the coupling with another of said circuits, said part having a neutralizing circuit connected across it and coupled with said disturbing circuit.

26. In combination, two transmitting circuits in proximity to each other, a source of high frequency energy of one frequency connected to one circuit, a source of high VZES frequency energy of a different frequency connected to the other circuit, and means connecting the two circuits for neutralizing` the mutual capacity between them at a desired frequency.

27. In combination, two circuits reactively related, local means for independently impressing an alternating potential across a portionof each of said circuits, and means interposed in circuit between circuits whereby interchange of energy, corresponding to the frequencies of the impressed potentials,

between said circuits in either direction is prevented.

28. In combination, two grounded antenna circuits operating at different frequencies and having mutual capacity, and a means interposed in circuit between said circuits whereby the capacitive reactance of said mutual capacity is neutralized for the frequency of each of said circuits.

In witness whereof, I hereunto subscribe my name this 22nd day of November A. D.,

HAROLD W. NICHOLS. 

